1. Field of the Invention
The invention relates generally to signal processing, and particularly to a method for efficiently calculating thresholds.
2. Description of the Related Art
Thresholding is a technique utilized in signal processing to identify and remove noise from the signal. There exists a variety of methods to perform thresholding on signals. One of the most common techniques is the Otsu method.
The Otsu method is a common thresholding method that is used in a wide array of areas such as noise reduction for human action detection, image segmentation based on lumen values, and segmentation of images with complex backgrounds. Otsu provided an algorithm that could be utilized to generate a threshold based on maximizing the variance between classes. The basic Otsu computation involves complex arithmetic operations such multiplications and divisions. Use of division does not pen-nit the implementation in high-speed low-cost hardware.
Building upon the Otsu method, Ku Chin Lin, in his paper “On improvement of the computation speed of Otsu's image threshold” Journal of Electronic Imaging 14(2), 023011 (April-June 2005), simplified the process by utilizing the derivative of the Otsu's mathematical formula. Additionally, the Lin method reduced the number of iterations required to find the threshold. While Lin's approach simplified the mathematical computation in each step, it still requires the use of division operations that make it impractical for implementation on low-cost digital signal processors.
All existing implementations of the Otsu method require the use of divides, which are resource-costly and require higher precision. Further, these implementations are not feasible for fixed-point digital signal processors for performing real-time processing of video data. Therefore, there exists a need for an improved method of calculating a threshold that does not require the use of divides.
In the following detailed description of exemplary embodiments of the invention, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration of specific exemplary embodiments in which the invention may be practiced.